Forming thin films on substrates using a porous carrier

ABSTRACT

The invention relates to a composite containing a porous carrier and an amphiphilic material. The composite may be employed in methods and systems for forming thin films on substrates.

RELATED APPLICATIONS

This application claims priority to provisional application Ser. No.60/350,096 filed Oct. 29, 2001, the contents of which are incorporatedherein.

FIELD OF THE INVENTION

The present invention generally relates to thin films. In particular,the present invention relates to forming a high quality thin film onsubstrate using a porous carrier.

BACKGROUND OF THE INVENTION

Polymerizable amphiphilic molecules and hydrolysable alkyl silanes areemployed to form thin films on various surfaces. Thin films havenumerous and diverse useful purposes. For example, a thin film may beformed on a lens for scratch resistance or on a metal for corrosionprotection.

It is difficult to form a thin film of amphiphilic molecules directly ona lens, so a silicon dioxide layer is initially formed on the lens in ananhydrous environment in a first chamber. The silica coated lens is thentransferred to a second chamber for deposition of the film ofamphiphilic molecules. During the transfer, the silica coated lens isexposed to water vapor in the air which hydrolyzes the surface andpermits subsequent strong adhesion between the amphiphilic molecules andthe lens. Forming the amphiphilic thin film in the same chamber as thesilica layer leads to corrosion of the interior of the chamber, thecontamination of the chamber preventing repeated use of the chamber forthe two step process without thorough cleaning, and the undesirableformation of a messy, difficult to clean film on the interior of thechamber. Nevertheless, in some instances, the requirement of twochambers can be cumbersome.

When forming a thin film on a substrate, a film forming material istypically dissolved in a solvent. The solvent/film forming materialmixture is then contacted with the substrate. One problem with forming athin film in this manner is that the solvent is typically toxic, and maybe hazardous due to flammability. In other words, the use of solventsthat can dissolve film forming materials may undesirably raise serioushealth and environmental concerns. Disposal of the solvents is a seriousenvironmental concern particularly in the case of oil base andhalocarbon solvents.

Furthermore, the use of such solvents leads to the generation ofhydrogen chloride gas as a by-product, which creates additional serioushealth hazards, unless a neutralizer trap is used and properly disposedaccording to EPA and OSHA regulations. Proper use and disposal is verydifficult in a working environment, especially since an operator musttrack such use. Hence, each operator and lab may require having toxicgas monitors or employ the use of vapor masks, which are uncomfortableto operator.

One recent development in the field of thin film formation is the use ofan ampuole to deliver a film forming material to a substrate. Using avapor phase coating process, an ampuole containing a film formingmaterial is placed in a vacuum chamber with the substrate. After avacuum is established, the ampuole breaks releasing the film formingmaterial which vaporizes and proceeds to form a film on the substrate.The ampuole is an easy to handle, convenient vehicle to charge thechamber with a film forming material. However, there are severalconcerns when using an ampuole in this manner.

First, when the ampuole breaks releasing the film forming material,broken glass may damage the substrate. Due to pressure differencesbetween the inside of the ampuole and the vacuum chamber, the ampuolebreaks with undesirably high force, projecting glass pieces throughoutthe chamber. A related problem is that the film forming material thenundesirably forms a film over the broken glass pieces in addition to thesubstrate, thereby lowering the amount of film forming material destinedfor the substrate.

Second, when the ampuole breaks with high force, the film formingmaterial tends to spurt out, leading to a non-uniform film on thesubstrate. The inability to control the release of the film formingmaterial raises the need to inspection and often cleaning of coatedsubstrates.

SUMMARY OF THE INVENTION

One aspect of the invention relates to a composite containing a porouscarrier and an amphiphilic material. The amphiphilic material is usefulfor forming thin films on substrates. The composite may thus be employedin methods and systems for forming thin films on substrates. Since theporous carrier is used to deliver the amphiphilic material to thechamber, damage to substrates is mitigated while uniform distribution ofamphiphilic material vapor is facilitated. Moreover, the porous carriermitigates splashing as the amphiphilic material is vaporized. Lesssplashing leads to less waste.

As a result, the thin film formed on the substrate using the compositeof a porous carrier impregnated with the amphiphilic molecules iscontinuous in nature. Pinholes and other film defects commonly observedin conventionally made thin films are minimized and/or eliminated.

Another aspect of the invention relates to a composite containing aporous carrier and a polyhedral oligomeric silsesquioxane amphiphilicmaterial. When using the polyhedral oligomeric silsesquioxaneamphiphilic material, it is unnecessary to expose the substrate to watervapor in the event a silica (or other metal oxide type coating) coatingis employed to improve adhesion. As a result, the formation of silicaand the amphiphilic thin film can be conducted in one chamber,simplifying the coating process.

BRIEF SUMMARY OF THE DRAWINGS

FIG. 1 is an illustration of a composite for forming thin films inaccordance with one aspect of the present invention.

FIG. 2 is an illustration of a composite for forming thin films inaccordance with another aspect of the present invention.

FIG. 3 is an illustration of a composite for forming thin films inaccordance with yet another aspect of the present invention.

FIG. 4 is a schematic view of a system for forming thin films inaccordance with one aspect of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Using a composite containing a porous carrier and amphiphlic material,uniform and continuous thin films can be efficiently formed onsubstrates without damaging the substrates. The porous carrier, akin toa metal sponge in certain instances, constitutes an advantageous vehiclefor facilitating the vapor deposition of a thin film made of anamphiphlic material.

Amphiphilic molecules have the intrisic ability to self assemble and/orself-polymerize in a thin film. Amphiphilic molecules typically havehead and tail groups (tail being a nonreactive, non-polar group and headbeing reactive, polar group). Amphiphilic molecules generally includepolymerizable amphiphilic molecules, hydrolyzable alkyl silanes,hydrolyzable perhaloalkyl silanes, chlorosilanes, polysiloxanes, alkylsilazanes, perfluoroalkyl silazanes, disilazanes, and silsesquioxanes.

The polar group or moiety of the amphiphile can be a carboxylic acid,alcohol, thiol, primary, secondary and tertiary amine, cyanide, silanederivative, phosphonate, and sulfonate and the like. The non-polar groupor moiety mainly includes alkyl groups, per fluorinated alkyl groups,alkyl ether groups, and per-fluorinated alkyl ether groups. Thesenon-polar groups may include diacetylene, vinyl-unsaturated or fusedlinear or branched aromatic rings.

In one embodiment, the amphiphilic molecule is represented by Formula I:R_(m)SiZ_(n)  (I)where each R is individually an alkyl, fluorinated alkyl, alkyl ether orfluorinated alkyl ether containing from about 1 to about 30 carbonatoms, substituted silane, or siloxane; each Z is individually one ofhalogens, hydroxy, alkoxy and acetoxy; and m is from about 1 to about 3,n is from about 1 to about 3, and m+n equal 4. In another embodiment, Ris an alkyl, fluorinated alkyl, an alkyl ether or a fluorinated alkylether containing from about 6 to about 20 carbon atoms. The alkyl groupmay contain the diacetylene, vinyl-unsaturated, single aromatic andfused linear or branched aromatic rings.

In another embodiment, the amphiphilic molecule is represented byFormula II:R_(m)SH_(n)  (II)where R is an alkyl, fluorinated alkyl, an alkyl ether or a fluorinatedalkyl ether containing from about 1 to about 30 carbon atoms; S issulfur; H is hydrogen; m is from about 1 to about 2 and n is from 0to 1. In another embodiment, R is an alkyl, fluorinated alkyl, an alkylether or a fluorinated alkyl ether containing from about 6 to about 20carbon atoms. The alkyl chain may contain diacetylene, vinyl, singlearomatics, or fused linear or branched aromatic moieties.

In yet another embodiment, the amphiphilic molecule is represented byRY, where R is an alkyl, fluorinated alkyl, an alkyl ether or afluorinated alkyl ether containing from about 1 to about 30 carbon atomsand Y is one of the following functional groups: —COOH, —SO₃H, —PO₃,—OH, and —NH₂. In another embodiment, R is an alkyl, fluorinated alkyl,an alkyl ether or a fluorinated alkyl ether containing from about 6 toabout 20 carbon atoms. The alkyl chain may contain diacetylene,vinyl-unsaturated, single aromatic, or fused linear or branched aromaticmoieties.

In still yet another embodiment, the amphiphilic molecule may includeone or more of the following Formulae (III) and (IV):CF₃(CF₂)₇CH₂CH₂—Si(CH₃)₂Cl  (III)CF₃(CF₂)₇CH₂CH₂—Si(OEt)₃  (IV)

In another embodiment, the amphiphilic molecule is a disilazanerepresented by Formula V:RSiNSiR  (V)where R is an alkyl, fluorinated alkyl, an alkyl ether or a fluorinatedalkyl ether containing from about 1 to about 30 carbon atoms. In anotherembodiment, R is an alkyl, fluorinated alkyl, an alkyl ether or afluorinated alkyl ether containing from about 6 to about 20 carbonatoms.

In another embodiment, the amphiphilic molecule is represented byFormula VI:R(CH₂CH₂O)_(q)P(O)_(x)(OH)_(y)  (VI)where R is an alkyl, fluorinated alkyl, an alkyl ether or a fluorinatedalkyl ether containing from about 1 to about 30 carbon atoms, q is fromabout 1 to about 10, and x and y are independently from about 1 to about4.

In still yet another embodiment, the amphiphilic molecule is formed bypolymerizing a silicon containing compound, such astetraethylorthosilicate (TEOS), tetramethoxysilane, and/ortetraethoxysilane.

Amphiphilic molecules (and in some instances compositions containingamphiphilic molecules) are described in U.S. Pat. Nos. 6,238,781;6,206,191; 6,183,872; 6,171,652; 6,166,855 (overcoat layer); 5,897,918;5,851,674; 5,822,170; 5,800,918; 5,776,603; 5,766,698; 5,759,618;5,645,939; 5,552,476; and 5,081,192; Hoffmann et al., and “Vapor PhaseSelf-Assembly of Fluorinated Monlayers on Silicon and German Oxide,”Langmuir, 13, 1877-1880, 1997; which are hereby incorporated byreference for their teachings of amphiphilic materials.

Specific examples of amphiphilic molecules and compounds that can behydrolyzed into amphiphilic materials include octadecyltrichlorosilane;octyltrichlorosilane; heptadecafluoro-1,1,2,2-tetrahydrodecyltrichlorosilane available from Shin Etsu under the trade designationKA-7803; hexadecyl trimethoxysilane available from Degussa under thetrade designation Dynasylan 9116; tridecafluorooctyl triethoxysilaneavailable from Degussa under the trade designation Dynasylan F 8261;methyltrimethoxysilane available from Degussa under the tradedesignation Dynasylan MTMS; methyltriethoxysilane available from Degussaunder the trade designation Dynasylan MTES; propyltrimethoxysilaneavailable from Degussa under the trade designation Dynasylan PTMO;propyltriethoxysilane available from Degussa under the trade designationDynasylan PTEO; butyltrimethoxysilane available from Degussa under thetrade designation Dynasylan IBTMO; butyltriethoxysilane available fromDegussa under the trade designation Dynasylan BTEO; octyltriethoxysilaneavailable from Degussa under the trade designation Dynasylan OCTEO;fluoroalkylsilane in ethanol available from Degussa under Dynasylan8262; fluoroalkylsilane-formulation in isopropanol available fromDegussa under Dynasylan F 8263; modified fluoroalkyl-siloxane availablefrom Degussa under Dynasylan® F 8800; and a water-based modifiedfluoroalkyl-siloxane available from Degussa under Dynasylan F 8810.Additional examples of amphiphilic molecules and compounds that can behydrolyzed into amphiphilic materials include fluorocarbon compounds andhydrolyzates thereof under the trade designation Optool DSX availablefrom Daikin Industries, Ltd.; silanes under the trade designationsKA-1003 (vinyltrichloro silane), KBM-1003 (vinyltrimethoxy silane),KBE-1003 (vinyltriethoxy silane), KBM-703 (chloropropyltrimethoxysilane), X-12-817H, X-71-101, X-24-7890, KP801M, KA-12 (methyldichlorosilane), KA-13 (methyltrichloro silane), KA-22 (dimethyldichlorosilane), KA-31 (trimethylchloro silane), KA-103 (phenyltrichlorosilane), KA-202 (diphenyldichloro silane), KA-7103 (trifluoropropyltrichloro silane), KBM-13 (methyltrimethoxy silane), KBM-22(dimethyldimethoxy silane), KBM-103 (phenyltrimethoxy silane), KBM-202SS(diphenyldimethoxy silane), KBE-13 (methyltriethoxy silane), KBE-22(dimethyldiethoxy silane), KBE-103 (phenyltriethoxy silane), KBE-202(diphenyldiethoxy silane), KBM-3063 (hexyltrimethoxy silane), KBE-3063(hexyltriethoxy silane), KBM-3103 (decyltrimethoxy silane), KBM-7103(trifluoropropyl trimethoxysilane), KBM-7803(heptadecafluoro-1,1,2,2-tetrahydrodecyl trimethoxysilane), and KBE-7803(heptadecafluoro-1,1,2,2-tetrahydrodecyl triethoxysilane) available fromShin Etsu.

Additional specific examples of amphiphilic materials includeC₉F₁₉C₂H₄Si(OCH₃)₃; (CH₃O)₃SiC₂H₄C₆F₁₂C₂H₄Si(OCH₃)₃; C₉F₁₉C₂H₄Si(NCO)₃;(OCN)₃SiC₂H₄Si(NCO)₃; Si(NCO)₄; Si(OCH₃)₄; CH₃Si(OCH₃)₃; CH₃Si(NCO)₃;C₈H₁₇Si(NCO)₃; (CH₃)₂Si(NCO)₂; C₈F₁₇CH₂CH₂Si(NCO)₃;(OCN)₃SiC₂H₄C₆F₁₂C₂H₄Si(NCO)₃; (CH₃)₃SiO—[Si(CH₃)₂—O-]_(n)—Si(CH₃)₃(viscosity of 50 centistokes);(CH₃O)₂(CH₃)SiC₂H₄C₆F₁₂C₂H₄Si(CH₃)(OCH₃)₂; C₈F₁₇CH₂CH₂Si(OCH₃)₃;dimethylpolysiloxane having a viscosity of 50 centistokes (KF96,manufactured by Shin Etsu); modified diemthylpolysiloxane having aviscosity of 42 centistokes and having hydroxyl groups at both terminals(KF6001, manufactured by Shin Etsu); and modified dimethylpolysiloxanehaving a viscosity of 50 centistokes and having carboxyl groups(X-22-3710, manufactured by Shin Etsu).

In another embodiment, the amphlphilic material contains a repeatingunit of a polyorganosiloxane introduced into a fluoropolymer. Thefluoropolymer having the repeating unit of a polyorganosiloxane can beobtained by a polymerization reaction of a fluoromonomer and apolyorganosiloxane having a reactive group as a terminal group. Thereactive group is formed by chemically binding an ethylenicallyunsaturated monomer (e.g., acrylic acid, an ester thereof, methacrylicacid, an ester thereof, vinyl ether, styrene, a derivative thereof) tothe end of the polyorganosiloxane.

The fluoropolymer can be obtained by a polymerization reaction of anethylenically unsaturated monomer containing fluorine atom(fluoromonomer). Examples of the fluoromonomers include fluoroolefins(e.g., fluoroethylene, vinylidene fluoride, tetrafluoroethylene,hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-diol), fluoroalkylesters of acrylic or methacrylic acid and fluorovinyl ethers. Two ormore fluoromonomers can be used to form a copolymer.

A copolymer of a fluoromonomer and another monomer can also be used asthe amphiphilic material. Examples of the other monomers include olefins(e.g., ethylene, propylene, isoprene, vinyl chloride, vinylidenechloride), acrylic esters (e.g., methyl acrylate, ethyl acrylate,2-ethylhexyl acrylate), methacrylic esters (e.g., methyl methacrylate,ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate),styrenes (e.g., styrene, vinyltoluene, alpha.-methylstyrene), vinylethers (e.g., methyl vinyl ether), vinyl esters (e.g., vinyl acetate,vinyl propionate, vinyl cinnamate), acrylamides (e.g.,N-tert-butylacrylamide, N-cyclohexylacrylamide), methacrylamides andacrylonitriles.

Amphiphilic molecules further include the hydrolyzation products of anyof the compounds described above. In particular, treating any of theabove described compounds with an acid or base yields amphiphilicmaterials ideally suited for forming thin film on substrates.

Amphiphilic molecules specifically include polyhedral oligomericsilsesquioxanes (POSS), and such compounds are described in U.S. Patents6,340,734; 6,284,908; 6,057,042; 5,691,396; 5,589,562; 5,422,223;5,412,053; J. Am. Chem. Soc. 1992,114,6701-6710; J. Am. Chem. Soc. 1990,112, 1931-1936; Chem. Rev. 1995, 95,1409-1430; and Langmuir, 1994, 10,4367, which are hereby incorporated by reference. The POSSoligomers/polymers contain reactive hydroxyl groups. Moreover, the POSSpolymers/oligomers have a relatively rigid, thermally stablesilicon-oxygen framework that contains an oxygen to silicon ratio ofabout 1.5. These compounds may be considered as characteristicallyintermediate between siloxanes and silica. The inorganic framework is inturn covered by a hydrocarbon/fluorocarbon outer layer enablingsolubilization and derivatization of these systems, which imparthydrophobic/oleophobic properties to the substrate surface in a mannersimilar as alkyltrichlorosilanes.

In one embodiment the POSS polymer contains a compound represented byFormula (VI):[R(SiO)_(x)(OH)_(Y)]  (VII)where R is an alkyl, aromatic, fluorinated alkyl, an alkyl ether or afluorinated alkyl ether containing from about 1 to about 30 carbonatoms; x is from about 1 to about 4; and y is from about 1 to about 4.In another embodiment, R is an alkyl, aromatic, fluorinated alkyl, analkyl ether or a fluorinated alkyl ether containing from about 6 toabout 20 carbon atoms; x is from about 1 to about 3; and y is from about1 to about 3. Such a compound can be made by stirring RSiX₃, such as analkyl trihalosilane, in water and permitting it to hydrolyze, using anacid or base (such as HCl or ammonium hydroxide, respectively) tofurther hydrolyze the first hydrolization product.

Examples of POSS polymers include poly(p-hydroxybenzylsilsesquioxane)(PHBS);poly(p-hydroxybenzylsilsesquioxane-co-methoxybenzylsilsesquioxane)(PHB/MBS); poly(p-hydroxybenzylsilsesquioxane-co-t-butylsilsesquioxane)(PHB/BS);poly(p-hydroxybenzylsilsesquioxane-co-cyclohexylsilsesquioxane)(PHB/CHS); poly(p-hydroxybenzylsilsesquioxane-co-phenylsilsesquioxane)(PHB/PS);poly(p-hydroxybenzylsilsesquioxane-co-bicycloheptylsilsesquioxane)(PHB/BHS); poly(p-hydroxyphenylethylsilsesquioxane) (PHPES);poly(p-hydroxyphenylethylsilsesquioxane-co-p-hydroxy-α-methylbenzylsilsesquioxane) (PHPE/HMBS);poly(p-hydroxyphenylethylsilsesquioxane-co-methoxybenzylsilsesquioxane)(PHPE/MBS);poly(p-hydroxyphenylethylsilsesquioxane-co-t-butylsilsesquioxane)(PHPE/BS);poly(p-hydroxyphenylethylsilsesquioxane-co-cyclohexylsilsesquioxane)(PHPE/CHS);poly(p-hydroxyphenylethylsilsesquioxane-co-phenylsilsesquioxane)(PHPE/PS);poly(p-hydroxyphenylethylsilsesquioxane-co-bicycloheptylsilsesquioxane)(PHPE/BHS); poly(p-hydroxy-a-methylbenzylsilsesquioxane) (PHMBS);poly(p-hydroxy-a-methylbenzylsilsesquioxane-co-p-hydroxybenzylsilsesquioxane)(PHMB/H BS);poly(p-hydroxy-a-methylbenzylsilsesquioxane-co-methoxybenzylsilsesquioxane) (PHMB/MBS);poly(p-hydroxy-α-methylbenzylsilsesquioxane-co-t-butylsilsesquioxane)(PHMB/BS);poly(p-hydroxy-a-methylbenzylsilsesquioxane-co-cyclohexylsilsesquioxane)(PHMB/CHS);poly(p-hydroxy-α-methylbenzylsilsesquioxane-co-phenylsilsesquioxane)(PHMB/PS);poly(p-hydroxy-α-methylbenzylsilsesquioxane-co-bicycloheptylsilsesquioxane)(PHMB/BHS); andpoly(p-hydroxybenzylsilsesquioxane-co-p-hydroxyphenylethylsilsesquioxane)(PHB/HPES).

The amphiphilic molecules are incorporated on and/or into a porouscarrier to form a composite that facilitates the film forming process.The composite may be stored in an air tight or otherwise protectedcontainer. The porous carrier may function and/or look like a sponge.

In order to facilitate loading the porous carrier with the amphiphilicmolecules, the amphiphilic molecules may be optionally combined with asolvent. Either the mixture of solvent and amphiphilic molecules or theamphiphilic molecules (without solvent) is then contacted with theporous carrier for a sufficient time to permit the mixture/amphiphilicmolecules to infiltrate the pores. In this connection, the porouscarrier may be dipped in the mixture/amphiphilic molecules or themixture/amphiphilic molecules may be sprayed or poured on the porouscarrier. Alternatively, the amphiphilic molecules may be melted andcontacted with the porous carrier, the amphiphilic molecules may becombined with a solvent, then contacted the porous carrier, or theamphiphilic molecules may be injected in the porous carrier using asyringe. Regardless of how the amphiphilic molecules are incorporatedinto the porous carrier, it is desirable that the amphiphilic moleculesare substantially uniformly distributed throughout the porous carrier.

Solvents to which the amphiphilic molecules may be combined aregenerally non-polar organic solvents. Such solvents typically includealcohols such as isopropanol; alkanes such as cyclohexane and methylcyclohexane; aromatics such as toluene, trifluorotoluene;alkylhaolsilanes, alkyl or fluoralkyl substituted cyclohexanes; ethers;perfluorinated liquids such as perfluorohexanes; and other hydrocarboncontaining liquids. Examples of perfluorinated liquids include thoseunder the trade designation Fluorinert T and Novec™ available from 3M.When combining the amphiphilic molecules with one or more solvents, heatmay be optionally applied to facilitate formation of a uniform mixture.

A film forming catalyst and/or a quencher may be combined with theamphiphilic material or mixture of amphiphilic material and solvent tofacilitate the film formation process. Film forming catalysts includemetal chlorides such as zinc chloride and aluminum chloride, and mineralacids while quenchers include zinc powders and amines. Each is presentin the amphiphilic material or mixture of amphiphilic material andsolvent in an amount from about 0.01% to about 1% by weight.

The porous carrier impregnated with the mixture of amphiphilic materialand solvent is treated to remove the solvent or substantially all of thesolvent by any suitable means. For example, evaporation or vacuumdistillation may be employed. After solvent is removed, or in the eventthe porous carrier is impregnated with amphiphilic material without theuse of solvent, heat is applied until a constant weight is achieved. Inthis instance, heating at a temperature from about 40 to about 100° C.is useful. In most instances, the amphiphilic material solidifies,becomes semi-solid, or becomes a low viscosity liquid and is retained inthe pores of the porous carrier.

The porous carrier may be made of any material inert to the amphiphilicmolecules, such as metals, metal oxides, and ceramics. When a metal isemployed as the porous carrier material, the porous carrier may bereferred to as a metal sponge. Examples of materials that may form theporous carrier include one or more of alumina, aluminum silicate,aluminum, brass, bronze, chromium, copper, gold, iron, magnesium,nickel, palladium, platinum, silicon carbide, silver, stainless steel,tin, titanium, tungsten, zinc, zirconium, Hastelloy®, Kovar®, Invar,Monel®, lnconel®, and various other alloys.

Such materials in powder, granuole, and/or fiber form are compressed toprovide the porous carrier, or compressed and sintered. Any resultantshape may be employed. Shapes of the compressed porous carrier materialsinclude cylindrical, spherical, oval, tablet, disc, plugs, pellets,cubes, rectangles, conical, of any size consistent with a particularapplication. Referring to FIGS. 1 to 3, various shapes/sizes of a porouscarrier are illustrated. In each figure, a porous material 10 containspores 12 which holds the amphiphilic molecules.

In one embodiment, the porous carrier contains pores having an averagepore size from about 1 micron to about 1,000 microns. In anotherembodiment, the porous carrier contains pores having an average poresize from about 5 microns to about 500 microns. In yet anotherembodiment, the porous carrier contains pores having an average poresize from about 10 microns to about 200 microns. In still yet anotherembodiment, the porous carrier contains pores having an average poresize from about 20 microns to about 100 microns. The size of the poresmay be controlled by adjusting the size of the particulates initiallycompressed together.

Examples of porous carriers include those under the trade designationMott Porous Metal, available from Mott Corporation; those under thetrade designation Kellundite available from Filtros Ltd.; and thoseunder the trade designations Metal Foam, Porous Metal Media andSinterflo®, available from Provair Advanced Materials Inc.

In one embodiment, the porous carrier has a porosity so that it canabsorb from about 0.001 g to about 5 g of amphiphilic material per cm³of porous carrier. In another embodiment, the porous carrier has aporosity so that it can absorb from about 0.01 g to about 2 g ofamphiphilic material per cm³ of porous carrier. In yet anotherembodiment, the porous carrier has a porosity so that it can absorb fromabout 0.05 g to about 1 g of amphiphilic material per cm³ of porouscarrier. In one embodiment in these porosity amounts, the amphiphilicmaterial includes the amphiphilic molecules and solvent. In anotherembodiment in these porosity amounts, the amphiphilic material includesthe amphiphilic molecules without solvent.

The methods and composites of the present invention are advantageous forproviding thin films on substrates. Substrates include those with porousand non-porous surfaces such as glasses, glass having an antireflectioncoating such as magnesium fluoride, silica (other metal oxides),germanium oxide, ceramics, porcelains, fiberglass, metals, and organicmaterials including thermosets such as polycarbonate, andthermoplastics. Additional organic materials include polystyrene and itsmixed polymers, polyolefins, in particular polyethylene andpolypropylene, polyacrylic compounds, polyvinyl compounds, for examplepolyvinyl chloride and polyvinyl acetate, polyesters and rubber, andalso filaments made of viscose and cellulose ethers, cellulose esters,polyamides, polyurethanes, polyesters, for example polyglycolterephthalates, and polyacrylonitrile.

Glasses specifically include lenses, such as eyewear lenses, microscopeslides, binocular lenses, microscope lenses, telescope lenses, cameralenses, video lenses, televison screens, computer screens, LCDs,mirrors, prisms, and the like. Substrates may have a primer layer of amaterial desired to improve adhesion between the substrate surface andthe amphiphilic molecules.

Employing the porous carrier of the present invention, the amphiphilicmolecules are applied as a thin film to a substrate surface using anysuitable thin film forming technique. The porous carrier contributes tothe efficient delivery of amphiphilic molecules to the substratesurface, while minimizing or eliminating damage to the substrate andminimizing waste of the amphiphilic molecules.

Film forming techniques involve exposing the substrate to theamphiphilic molecules incorporated on the porous carrier in a chamber orclosed environment under at least one of reduced pressure, elevatedtemperature, irradiation, and power. Preferably, reduced pressure and/orelevated temperatures are employed. The reduced pressure, elevatedtemperatures, irradiation, and/or power imposed induce vaporization orsublimation of the amphiphilic molecules into the chamber atmosphere andsubsequent self assembly and/or self-polymerization on the substratesurface in a uniform and continuous fashion thereby forming the thinfilm.

In one embodiment, the substrate is exposed to the amphiphilic moleculesunder a pressure from about 0.000001 to about 760 torr. In anotherembodiment, the substrate is exposed to the amphiphilic molecules undera pressure from about 0.00001 to about 200 torr. In yet anotherembodiment, the substrate is exposed to the amphiphilic molecules undera pressure from about 0.0001 to about 100 torr.

In one embodiment, the composite/porous carrier is heated to atemperature from about 20 to about 400° C. In another embodiment, thecomposite/porous carrier is heated to a temperature from about 40 toabout 3500 C. In yet another embodiment, the composite/porous carrier isheated to a temperature from about 50 to about 300° C. Only thecomposite/porous carrier needs to be at the temperature described aboveto induce film formation. The substrate is at about the same or at adifferent temperature as the composite/porous carrier in the chamber.The composite/porous carrier is at about the same or at a differenttemperature as the atmosphere of the chamber. The substrate is at aboutthe same or at a different temperature as the atmosphere of the chamber.In one embodiment, each of the substrate, composite, and atmosphere isat a temperature from about 20 to about 400° C.

In one embodiment, the amount of amphiphilic material used is from about1×10⁻³ mmole/ft³ to about 10 mmole/ft³ of chamber volume. In anotherembodiment, the amount of amphiphilic material used is from about 1×10⁻²mmole/ft³ to about 1 mmole/ft³ of chamber volume.

In one embodiment, the substrate and the amphiphilic material remains incontact for a time from about 10 seconds to about 24 hours (underspecified temperature and pressure). In another embodiment, thesubstrate and the amphiphilic material remains in contact for a timefrom about 30 seconds to about 1 hour. Alternatively, time limitationscan be ignored so long as the film thickness is monitored so that theprocess may be terminated after the desired thickness is achieved.

The film formation rate is primarily dependent upon one or more of theidentity of the amphiphilic material, the identity of the porouscarrier, and the film formation conditions (temperature, pressure, andthe like). In one embodiment, the film formation rate is about 0.01nm/sec or more and about 1 nm/sec or less (nm in film thickness). Inanother embodiment, the film formation rate is about 0.05 nm/sec or moreand about 0.5 nm/sec or less.

General examples of film forming techniques include vacuum deposition;vacuum coating; box coating; sputter coating; vapor deposition orchemical vapor deposition (CVD) such as low pressure chemical vapordeposition (LPCVD), plasma enhanced chemical vapor deposition (PECVD),high temperature chemical vapor deposition (HTCVD); and sputtering. Suchtechniques are known in the art and not described for brevity sake.

Vapor deposition/chemical vapor deposition techniques and processes havebeen widely disclosed in literature, for example: Thin Solid Films,1994, 252, 32-37; Vacuum technology by Ruth A. 3^(rd) edition, ElsevierPublication, 1990, 311-319; Appl. Phys. Left. 1992, 60, 1866-1868;Polymer Preprints, 1993, 34,427-428; U.S. Pat. Nos. 6,265,026;6,171,652; 6,051,321; 5,372,851; and 5,084,302, which are herebyincorporated by reference for their teachings in forming films ordepositing organic compounds on substrates.

Referring to FIG. 4, a method and system for forming thin films isdescribed. Generally speaking, a chamber 20 such as a vacuum chamber isemployed for use in the present invention. The chamber may be aninsulated rectangular metal box having a door which is sealed by agasket when closed and allows insertion and removal of items. The boxcan have an inside chamber that is optionally attached to a high vacuumpump 22 capable of drawing a vacuum of, for example, 0.0001 torr.Examples of chambers include those under the trade designation Satis,such as MC LAB 260, MC LAB 360, 900 DLS, 1200 TLS, and 150 availablefrom Satis Vacuum AG; those under the trade designation Univex, such as300, 350, and 400 available from Leybold Vacuum; those under the tradedesignation Integritye 36, 39, 44, and 50 available from Denton Vacuum;and those under the trade designation Balinit® available from Balzers.

The chamber can be equipped with separate heating devices for at leastone of heating the chamber 24, heating/vaporizing the amphiphilicmaterial 26 and heating the substrates 28. A number of different devicessuch as resistance electrodes, a resistance heater, an induction coil,or an electron or laser beam can be used for rapidly heating theamphiphilic materials to a high temperature for vaporization. Anelectric heater block may be used for this purpose. The heater may heata crucible 30 in which the composite 32 is placed.

The substrates 34 to be coated with a thin, hydrophobic film inaccordance with the invention are placed inside the chamber, in anysuitable position. The composite 32 of a porous carrier and amphiphilicmaterial is also placed in contact with a heating device 26 inside thechamber 20 and the door is closed. Although a cone arrangement is shown,the composite 32 of a porous carrier and amphiphilic material andsubstrates 34 may be positioned in any manner. A strong vacuum fromabout 2×10⁺² to about 5×10⁻⁴ torr is optionally applied to the chamber20. A valve 36 connecting the pump 22 to the chamber 20 is closed tokeep the chamber 20 at constant high vacuum. The amphiphilic material isheated quickly to vaporize the material. The gas phase amphiphilicmolecules spread uniformly and very quickly throughout the chamber 20.As the amphiphilic molecules vaporize, the vacuum inside the chamber mayrise slightly but remains within the range from about 2×10⁺² to about5×10⁻⁴ torr. The chamber 20 is kept in this condition for a time fromabout 10 seconds to about 60 minutes or the thickness is monitored by aquartz crystal that can be mounted in the chamber (to obtain a desiredthickness). During this time the amphiphilic molecules self-assemble andattach themselves to the surface of the substrates 34 and form acontinuous, uniform thin film. The substrate 34 may be rotated topromote uniform application of the amphiphilic material over thesubstrates 34.

After the selected time, the vacuum pump valve 36 is opened to evacuatethe excess gas phase amphiphilic material from the chamber 20. A coldtrap or condenser may be optionally employed between the chamber and thepump to condense and trap the excess amphiphilic material vapor so thatit does not escape to the atmosphere. Clean air is let into the chamber20 through another valve 38 thereby bringing it up to atmosphericpressure and the chamber 20 is opened to remove the coated substrates34.

The film forming composition may be characterized by FTIR and/or NMRusing known methods in the art. Other chemical properties such as % ofhydroxyl groups may be determined by methods known in the art such asU.S. Pat. No. 4,745,169. Still other physical properties andspectroscopic characterization methods may be employed and are known inthe art.

The amphiphilic material and/or film formed therefrom has reactivehydroxyl groups, which become involved in chemical bonding (hydrogenand/or covalent) to the substrate. As the substrate surface reacts withmoisture (airborne water molecules), making covalent bonds to thesurface, similar to self-assembley of layers, thus providing permanenttransparent uniform thin film, which is resistant to many drasticconditions; that is, retaining its excellent hydrophobic/oleophobicproperties.

The film provides several advantages on these surfaces including scratchresistance, protection of anti-reflective coatings on eyewear lenses,protect surfaces from corrosion, moisture barrier, friction reduction,anti-static, stain resistance, fringerprint resistance, and the like.The film is typically hydrophobic in nature.

The thin film formed on the substrate using the composite of a porouscarrier impregnated with the amphiphilic molecules has a uniformthickness over the substrate. In one embodiment, the thickness of theresultant thin film is from about 1 nm to about 250 nm. In anotherembodiment, the thickness of the resultant thin film is from about 2 nmto about 200 nm. In yet another embodiment, the thickness of theresultant thin film is from about 5 nm to about 100 nm. In still yetanother embodiment, the thickness of the resultant thin film is fromabout 8 nm to about 20 nm. The thickness of the thin film may becontrolled by adjusting the deposition parameters, for example, thelength of time the substrate and the composite remain in the chamberunder at least of reduced pressure, elevated temperature, irradiation,and/or power.

In one embodiment, the thin film is relatively uniform in that, assumingthe substrate has a planar surface, the thickness of the thin film doesnot vary by more than about 25 nm over the surface of the planar portionof the substrate. In another embodiment, the thin film is relativelyuniform in that the thickness of the thin film does not vary by morethan about 15 nm over the surface of the planar portion of thesubstrate.

The thin film formed on the substrate using the composite of a porouscarrier impregnated with the amphiphilic molecules is continuous innature. In other words, pinholes and other film defects in thin filmsmade in accordance with the present invention are minimized and/oreliminated.

In one embodiment, when using a POSS polymer as the amphiphilic materialand a glass as the substrate, formation of a layer of silica (or othermetal oxide) and amphiphilic material thin film may be conducted in asingle chamber. This is because it is not necessary to expose the silicalayer to water vapor when forming POSS polymer amphiphilic materiallayer thereover. Moreover, the formation of any POSS polymer amphiphilicmaterial layer on the interior of the chamber is not harmful, and doesnot prevent subsequent and repeated use of the chamber for theaforementioned two step process.

The following examples illustrate the present invention. Unlessotherwise indicated in the following examples and elsewhere in thespecification and claims, all parts and percentages are by weight, alltemperatures are in degrees Centigrade, and pressure is at or nearatmospheric pressure.

Example 1

Three liters of distilled water is placed in a 5 l beaker. The beaker isthen chilled to about 5° C. and the temperature is maintained bycirculation through a chiller to maintain the temperature, however anymethod known in the art for maintaining temperature, such as adding icemay be employed. Octadecyltrichlorosilane (300 g) is added dropwisewhile stirring and maintaining the temperature. The solution is thenhydrolyzed to yield a fine crystalline material. The reaction mixture isfurther stirred for approximately 30 minutes while continuing tomaintain temperature. The reaction mixture is then allowed to return toroom temperature while being stirred. After returning to roomtemperature, the reaction mixture is stirred for approximately 10 hours.The reaction mixture is then filtered and washed with water to removeall acid, and then dried. While the mixture is air dried and then ovendried at 95° C. for 2 hours, other methods of drying as are known in theart may alternatively be utilized. After drying the mixture, a whitepowder having a melting point of 70- 72° C. is provided.

Example 2

The procedure of Example 1 is repeated except thatheptadecafluoro-1,1,2,2-tetrahydrodecyl trichlorosilane is used in placeof octadecyltrichlorosilane. After drying the mixture, a white powderhaving a melting point of 67° C. is provided.

Example 3

The procedure of Example 1 is repeated except that octyl trichlorosilaneis used in place of octadecyltrichlorosilane. After drying the mixture,a very thick clear oil is provided.

Example 4

Hexadecyl trimethoxysilane (25 g), 15 ml of distilled water, 40 ml of2-propanol and 2 ml of concentrated HCl are stirred in a 250 ml flask.The mixture becames a white thick precipitate in a few minutes andbecomes difficult to stir. An additional 100 ml of a 50:50 water-2propanol mixture is added and the reaction mixture is stirred at roomtemperature for 10 hours and later heated to 70° C. for 2 hours to fullyhydrolyze and yield a fine powder. Isolation and filtration are carriedout as per Example 1. The reaction mixture is then dried in an oven at98° C. for 2 hours. The mixture becames oily and solidified on standingat room temperature, and yielded a white, waxy solid, having a meltingpoint of 65° C.

Example 5

The procedure of Example 4 is repeated except that a 1:1 molar ratio oftridecafluorooctyl triethoxysilane and hexadecyl trimethoxysilane isused in place of hexadecyl trimethoxysilane. A semi-solid is provided.

Example 6

Tridecafluorooctyl triethoxysilane and hexadecyl trimethoxysilane havingvarying weight ratios are mixed together. In addition, tetraethoxysilaneis added so as to comprise about 5% to about 10% of total weight of themixture. The mixture is then and hydrolyzed under the experimentalconditions of Examples 4 and 5, however zinc 2-ethylhexoate (zincoctoate) is added as catalyst for cross-linking agent to the hydrolyzedtetraethoxysilane to increase the number of reactive sites. Alcohol andwater are removed using a rotavap at reduced pressure. The mixtureyielded a white paste semi-solid.

While the invention has been explained in relation to certainembodiments, it is to be understood that various modifications thereofwill become apparent to those skilled in the art upon reading thespecification. Therefore, it is to be understood that the inventiondisclosed herein is intended to cover such modifications as fall withinthe scope of the appended claims.

1. A method of forming a thin film on a substrate, comprising: providingthe substrate in a chamber; inserting a composite comprising a metallicporous carrier and an amphiphilic material into the chamber, wherein theamphiphilic material is represented by Formula I:R_(m)SiZ_(n)  (I) where each R is individually fluorinated alkyl orfluorinated alkyl ether containing from about 1 to about 30 carbonatoms; each Z is individually one of hydrogen, halogens, hydroxy, alkoxyand acetoxy; and m is from about 1 to about 3, n is from about 1 toabout 3, and m+n equal 4; in the chamber, setting at least one of atemperature of the composite from about 20 to about 400° C. and apressure from about 0.000001 to about 760 torr to induce vaporization ofthe amphiphilic material; and recovering the substrate having the thinfilm thereon.
 2. The method of claim 1, wherein the substrate comprisesat least one of a glass, a glass having an antireflection coatingthereon, silica, germanium oxide, a ceramic, porcelain, fiberglass, ametal, a thermoset, and a thermoplastic.
 3. The method of claim 1,wherein the metallic porous carrier comprises pores having an averagepore size from about 1 micron to about 1,000 microns.
 4. The method ofclaim 1, wherein the metallic porous carrier has a porosity so that itabsorbs from about 0.001 g to about 5 g of amphiphilic material per cm³of metallic porous carrier.
 5. The method of claim 1, wherein themetallic porous carrier comprises at least one of aluminum, brass,bronze, chromium, copper, gold, iron, nickel, palladium, platinum,silver, stainless steel, tin, titanium, tungsten, zinc, and zirconium.6. The method of claim 1, after setting at least one of the temperatureand the pressure, keeping the substrate in the chamber for a time fromabout 10 seconds to about 24 hours.
 7. The method of claim 1, whereinwhere each R is fluorinated alkyl ether containing from about 1 to about30 carbon atoms.
 8. The method of claim 1, wherein the pressure is setprior to setting the temperature.
 9. The method of claim 1, wherein thetemperature is set from about 40 to about 350° C. and the pressure isset from about 0.00001 to about 200 torr.
 10. The method of claim 1,wherein the thin film is formed at a rate of about 0.01 nm/sec or moreand about 1 nm/sec or less.
 11. The method of claim 1, wherein the thinfilm has a thickness from about 1 nm to about 250 nm.
 12. A system forforming a thin film, comprising: a film forming chamber in communicationwith at least one of a heat source and a vacuum system; a compositecomprising a metallic porous carrier and an amphiphilic materialpositionable within the film forming chamber, the amphiphilic materialcomprising at least one of a polyhedral oligomeric silsesquioxane and acompound represented by Formula I:R_(m)SiZ_(n)  (I) where each R is individually fluorinated alkyl orfluorinated alkyl ether containing from about 1 to about 30 carbonatoms; each Z is individually one of hydrogen, halogens, hydroxy, alkoxyand acetoxy; and m is from about 1 to about 3, n is from about 1 toabout 3, and m+n equal 4; and a substrate on which the thin film isformed positionable within the film forming chamber.
 13. The system ofclaim 12, wherein the film forming chamber is in communication with aheat source and a vacuum system.
 14. The system of claim 12, wherein themetallic porous carrier comprises pores having an average pore size fromabout 5 microns to about 500 microns.
 15. The system of claim 12,wherein the composite comprises from about 0.01 g to about 2 g of theamphiphilic material per cm³ of metallic porous carrier.
 16. The systemof claim 12, wherein the composite further comprises at least one of anon-polar organic solvent, a film forming catalyst, and a quencher. 17.A film forming composite, comprising: a metallic porous carriercomprising pores having an average pore size from about 1 micron toabout 1,000 microns; and an amphiphilic material, the amphiphilicmaterial comprising at least one of a polyhedral oligomericsilsesquioxane and a compound represented by Formula I:R_(m)SiZ_(n)  (I) where each R is individually fluorinated alkyl orfluorinated alkyl ether containing from about 1 to about 30 carbonatoms; each Z is individually one of hydrogen, halogens, hydroxy, alkoxyand acetoxy; and m is from about 1 to about 3, n is from about 1 toabout 3, and m+n equal 4, wherein the metallic porous carrier has aporosity so that it absorbs from about 0.001 g to about 5 g ofamphiphilic material per cm³ of metallic porous carrier.
 18. The filmforming composite of claims 17, wherein the metallic porous carriercomprises at least one of aluminum, brass, bronze, chromium, copper,gold, iron, nickel, palladium, platinum, silver, stainless steel, tin,titanium, tungsten, zinc, and zirconium.
 19. The film forming compositeof claims 17, wherein the metallic porous carrier comprises pores havingan average pore size from about 5 microns to about 500 microns and theporous carrier has a porosity so that it absorbs from about 0.01 g toabout 1 g of amphiphilic material per cm³ of metallic porous carrier.20. The film forming composite of claims 17, wherein the composite hasone of a cylindrical shape, a spherical shape, an oval shape, a tabletshape, a disc shape, a plug shape, a pellet shape, a cubical shape, arectangular shape, and a conical shape. 21-23. (canceled)